Police said officers were called to a home about 2 a.m. Sunday to assist medics responding to a call of an injured child, KPTV, Portland, reported.
They determined the mother had attempted the medical procedure on the child, KPTV said.
The child was taken to the hospital and is expected to survive, Portland police Sgt. Pete Simpson said.
Detectives from the department's child abuse team and state officials were investigating.
No arrests had yet been made, Simpson said.
Couple mistakenly served bag of cash at McDonald's drive-thru
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'